1 First of all go to backup exec log on account in backup Exec and ensure you have got system log on account selected as default log on account and your backup exec services are running to with same account you can check this by going to services for windows

2 Ensure then the account used to backup and restore for exchange is part of Organization management ,domain admin,administrators group and exchange servers group

3 Once checked and configured as mention above restart the services once on Media server and Exchange server and then try doing restore it should work fine this time

Additionally ensure remote agent is installed on all nodes of Exchange(Mailbox node, CAS node)if it is DAG

Hope that helps

Thanks

Sameer

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